A typical vehicle exhaust system includes an assembly of tubes, or pipes, that provide transport of engine exhaust gases. Each individual pipe section is connected to another pipe section to form a complete exhaust system assembly. Such connections are usually either telescopic or as an end-to-end abutting connection. To be effective, the connection formed between these pipes should provide a suitable fluid-tight seal against exhaust gas leakage. The connection should also have a high degree of mechanical strength and be capable of being disassembled for possible maintenance and repair.
Pipe couplers are often used for exhaust systems where the pipe sections are axially joined in an end-to-end configuration. A conventional pipe coupler includes a band having a generally circular conformation and terminating in opposing connecting flanges that can be drawn together or loosened via a fastener or other tightening mechanism. A reaction member can be provided between the flanges to help provide an even distribution of circumferential forces on the pipes as the band is tightened. Often, the pipe coupler will include an internal split sealing sleeve with mating circumferential ends that engage each other during tightening to produce a gas-tight seal. U.S. application Publication No. 2002/0014772 A1 published Feb. 7, 2002 (now U.S. Pat. No. 6,758,501 to Amedure et al.) is an example of such a pipe coupler having a split sealing sleeve, and the entire contents of that published application are hereby incorporated by reference.
In the Amedure patent, each tongue of the split sealing sleeve shown in FIGS. 3-7 comprises a pair of spring members that during tightening engage converging side edges of their associated groove with the spring members being deflected inwardly towards each other as they are forced farther into the groove. The outward force of the spring arms against the angled side edges of the groove maintain good contact with the groove side edges to provide a seal against gas leakage. In this Amedure patent, the tongue-and-groove mating portions are located towards the axial extents of the sleeve. In particular, the center of each tongue-and-groove mating portion is spaced in from its nearest axial end of the sealing sleeve by a distance of about 17-22% of the total axial width of the sleeve.
Ribbed band clamps that were originally designed for catalytic converters and diesel particulate filters having diameters much larger than typical automotive exhaust pipes are shown and described in U.S. patent application Publication No. 2003/0015872 A1 published Jan. 23, 2003 (now U.S. Pat. No. 6,877,780 to Potts et al.), the entire contents of which are hereby incorporated by reference. The ribs of the band clamp engage corresponding beads or ribs of the exhaust system canisters (or other tubular bodies) being joined to provide the joint with good strength against tensile (pull-apart) forces. For protection against gas leakage, one of the disclosed clamps uses a gasket along with a version of the tongue-and-groove sealing structure from Amedure's patent in which the circumferential ends of the band itself have a tongue-and-groove mating structure located within ribs of a separate pair of strap sections that are provided as a part of the tightening mechanism.
Although the band clamps of the Potts patent can be used for exhaust component canisters and smaller diameter pipes as well, the inventors have found that the design of the band clamps disclosed in the Potts patent do not provide a sufficiently strong and gas-tight connection for certain automotive exhaust applications. Similarly, although the pipe coupler of the Amedure patent is suitable for many automotive applications, there continues to be a demand within the automotive industry to develop pipe couplers that offer increased performance in terms of pull-apart strength, gas tightness, and/or various other parameters.